Although a previous study from our laboratory reported that serum KL-6 levels at diagnosis increased only in the life-threatening types, such as the DAD and CIP patterns, of drug induced ILDs [27], absolute serum KL-6 levels at the onset of EGFR-TKIs induced ILD did not correlate with clinical outcomes in the present study. Here, MUC1 is linked to interstitial lung disease.